1. Field of the Invention
The invention relates to automation technology and, more particularly, to a method implemented in a redundant system for supplying a load with a voltage, where a first output voltage for controlling the load is switched using a first output of a first output module and a second output voltage is switched to the first output module using a second output of a second output module.
The invention further relates to a system for redundant supply of a voltage to a load, comprising a first output module having a first output, which is connected by a first connection to a first load terminal of the load, where a second load terminal of the load is connected by a second connection to a ground terminal of the first output module to form a first electrical current path. The second output module is connected in a similar manner to the load by the second output to achieve the redundancy, similarly to the first output module, so that a second electrical current path is formed, i.e., the system has a redundant structure through the connection of the two output modules.
2. Description of the Related Art
It is known to employ methods, systems or modules in, for example, digital output modules that are typically used in safety-oriented devices, such as in automation technology. In particular, detecting a broken wire plays an important role. On the one hand, the safety of the process must be guaranteed, while on the other hand the safety of life and limb, for example, the safety of the people operating the process, must be guaranteed. In these safety applications, redundant connection of the output modules continues to play a further important role.
In the area of automation technology, redundancy means the presence of functionally identical or comparable resources of a technical system. Here, at least two systems or two output modules are thus present to guarantee redundant operation.
Starting from a redundantly connected system of two automation modules, it is known that, for example, two digital output modules for driving a load are connected in parallel by their outputs to the load. As a result, if one output module fails, then the transfer of power for the load is guaranteed by the other module. Both output modules are equipped with a wire break detection system in such cases. In the event that one of the two modules detects a wire break to the load, then the module provides a notification of the wire break to the other module over a separate communication interface installed between the redundantly-connected output modules. Here, the disadvantage is that additional wiring for communication must be installed between the modules.
It is also necessary to supply the modules with an operating voltage. As a result, it is further disadvantageous that with redundant connection, especially with fluctuations of the supply, a detected wire break can be diagnosed prematurely although no actual wire break is actually present.